3D sedimentary architecture showing the inception of an Ice Age

Abstract

Northeast Atlantic climate shifted into the Quaternary Ice Age around 2.6 M yr ago. Until now, however, the detailed changes associated with this inception of an Ice Age have remained obscure. New high-quality three-dimensional seismic data reveal a detailed geological record of buried surfaces, landforms and sedimentary architecture over vast parts of the Norwegian North Sea. Here, we show the sequence of near-coast geological events spanning the Northeast Atlantic inception of an Ice Age. We identify the location of immediate pre-glacial fluvially derived sandy systems where rivers from the Norwegian mainland built marine deltas. The stratigraphic position of a large submarine channel, formed by enhanced meltwater from initial build-up of local glaciers, is also shown. Finally, we document the transition to full ice-sheet growth over Scandinavia from the ice sheet's earliest position to the later pattern of debris-flow lobes reaching the present-day shelf edge.

Pliocene–Pleistocene glacimarine shelf to slope processes in the south‐western Barents Sea

“…The record of global ice volume, as indicated by deep‐sea oxygen isotopes (Figure 2) (Miller et al., 2011, 2020; Zachos et al., 2008), suggests that ice volumes generally increased through the Pleistocene and underwent a significant increase after the Mid‐Pleistocene Transition. However, palaeo‐glaciological studies have revealed that extensive glaciation occurred in the Northern Hemisphere during the Early Pleistocene (Batchelor et al., 2019 and references therein), with the Scandinavian Ice Sheet first advancing to the palaeo‐shelf break in the northern North Sea close to the onset of the Pleistocene (Ottesen et al., 2018; Løseth et al., 2020). Terrestrial evidence suggests that the Laurentide Ice Sheet reached its maximum southerly extent in North America during the Early Pleistocene (Balco & Rovey, 2010; Balco et al., 2005; Rovey & Balco, 2010), whereas seismic data from other TMFs along the Northeast Atlantic margin contain evidence for shelf‐break glaciation during this time (Hjelstuen et al., 1996; Rydningen et al., 2016; Montelli et al., 2017; Newton & Huuse, 2017; Lasabuda et al., 2018; Newton et al., 2018).…”

A regional CO2 containment assessment of the northern Utsira Formation seal and overburden, northern North Sea

“…The foresets within the Seal Interval are sand rich (>50%) from the ESP (western system), but sand poor (<10%; except for a few wells in Blocks 30/6 and 31/4, where sandstone content is <25%) from the NM (eastern system) (Figure 5b). The different depositional system types can be attributed to this lithological contrast; sediments from the east are derived from a glacial system and mainly deposited through glaciogenic debris flows (Løseth et al., 2020), whereas sediments from the west are derived from a nonglacial, fluvio‐deltaic system and deposited through sand‐rich turbidity currents. There are high sand percentages in the wells in the Tampen Spur region, the distribution of which is discussed in Section 5.3.…”

“…up to the URU) was divided into six units, which represent the depositional evolution of the basin (Figure 4). Previous studies take a similar approach by splitting the stratigraphy into four (Batchelor et al., 2017; Løseth et al., 2020; Ottesen et al., 2014, 2018) or three (Gregersen & Johannessen, 2001, 2007) seismic stratigraphic units. Units were defined through manual interpretation of the seismic reflection data considering stratal geometries, amplitudes and thickness patterns that highlight the main bounding surfaces, using a combination of 2D and 3D auto‐tracking tools (Petrel™ software).…”

“…The overlying sediments that comprise the seal and overburden of the Utsira Fm. are termed the Naust Formation in the Norwegian Sea (Dalland et al, 1988), and this nomenclature has been extended into the North Sea stratigraphy (Batchelor et al, 2017;Eidvin et al, 2013;Løseth et al, 2020;Ottesen et al, 2014Ottesen et al, , 2018. In the northern North Sea, the Naust Fm.…”

“…represents up to 1,000 m of sediments in the basin centre (Eidvin et al, 2013;Ottesen et al, 2012Ottesen et al, , 2014. It has been subdivided into four stratigraphic intervals (A, B, C and D), which are intervened by the Upper Regional Unconformity (URU); a diachronous feature that is present over much of the North Sea, and is related to significant glacial influence and erosion of the Norwegian Channel (Batchelor et al, 2017;Løseth et al, 2020;Ottesen et al, 2014Ottesen et al, , 2018. Beneath the URU, the Naust Fm.…”